“Stomach flu” shouldn’t be confused with influenza. The term refers to gastroenteritis, an irritation or inflammation of the stomach lining or intestines. Influenza is only caused by the flu virus, while gastroenteritis can be triggered in a variety of ways.
When stomach flu is caused by a viral or bacterial infection it can be highly contagious, and will often spread throughout families. Frequent hand-washing – and practicing good hygiene in the kitchen, the bathroom and while changing a baby – can help reduce the risk.
Causes of stomach flu include:
• Food-borne bacteria, such as Campylobacter, Clostridium, E. coli, Listeria, Salmonella or Shigella
• Stomach virus, including adenovirus, astrovirus, norovirus and rotavirus
• Water-borne parasites, such as giardia and cryptosporidium. (These are seldom an issue in the developed world, although they can be contracted from untreated stream or pond water.)
• Reaction to a food allergy, such as to dairy products or shellfish
Symptoms of stomach flu may include:
• stomach pain
• abdominal cramps
• swollen lymph glands
Stomach flu poses the greatest danger for infants, pregnant women, the elderly, people who are malnourished, and those with compromised immune systems.
You should also seek medical treatment if you (or your child) have the following symptoms:
• dehydration (see below)
• high fever (above 101◦F)
• blood in the vomit or stool, indicated by a dark brown or black color or “coffee ground” consistency
• a swollen abdomen, or pain in the right lower abdomen, indicating inflammatory disease
• headache and stiff neck
• vomiting that lasts more than 48 hours
The risk of dehydration
Especially when accompanied by diarrhea, vomiting or fever, stomach flu can cause unhealthful fluid loss. This can include a loss of electrolytes, such as sodium and potassium, which are important for nerve and muscle function and help keep the body’s fluids in balance.
Children have a higher risk of dehydration than adults, and young children may become dehydrated quickly without being able to communicate their distress, says Marsha Kay, M.D., section head of the Department of Pediatric Gastroenterology at the Cleveland Clinic.
If a child is dehydrated, have him or her sip fluids (especially an electrolyte drink) and seek medical attention.
Symptoms of dehydration include:
• increased thirst
• decreased urination
• decreased tears
• dry lips and mouth
• lack of skin elasticity
• rapid breathing
• rapid pulse
• weakness or dizziness
Severe dehydration is a medical emergency, and you should get help immediately. Symptoms include:
• difficulty or inability to drink
• parched mouth or tongue
• minimal or no urination
• weak pulse
• deep breathing
• cool extremities
• greater than 9 percent weight loss
• sunken eyes (or, in infants, a sunken fontanelle – the soft spot on top on the head)
• severe dizziness, lethargy or unconsciousness